Applied Mechanics and Materials Vols. 813-814

Abstract: The objective of this study is to evaluate the wear progression of cryogenically treated and untreated tungsten carbide inserts during face milling of Grey Cast Iron which is a commonly used material in machine tool beds and automotive components due to low cost, high vibration damping capability, and easiness of manufacturing. Commercially available uncoated Tungsten Carbide insert with around 6% Cobalt (Co) content were selected for the study and flank wear and nose wear were taken as the performance evaluation criteria. The results show that the cryogenically treated samples have better wear resistance than the untreated inserts which could be ascribed to the martensitic phase transformation of Co from α-Co (FCC) to ε-Co (HCP) during the cryogenic treatment.

Abstract: Production cost is dependent on the life of the Tool. Because of enormous heat generation during the material removal process, life of the tool decreases. Tool life will be enhanced by cryogenic treatment which minimises the temperature at tool tip interface. Taguchi technique was employed to get optimum number of experiments for turning white cast iron after the cryogenic treatment and before cryogenic treatment. The correlation between four main factors such as speed, feed, depth of cut, tool condition and responses such as surface roughness, tool tip temperature were analysed. Mathematical model was formulated for tool tip temperature, and surface roughness. The error for the mathematically formulated model was observed to be less than 5%.The present work indicates that cryogenically treated tool have better surface finish . From the anova analysis it is inferred that tool tip temperature and surface roughness substantially reduced while using cryogenically treated tool. It was observed that cutting forces was more influenced by cutting speed of the tool followed by tool condition. Hardness of the tool insert showed improvement because of coatings.

Abstract: The most common and serious defect in casting is porosity, which is the result of two phenomena namely, insufficient feeding and hydrogen precipitation during solidification. Formation of porosity defect in aluminum alloy is a complex process. Researchers have modeled the pore formation using analytical solution, criteria function and heat transfer simulations. Each model has its own advantages and disadvantages. This paper review the various papers which deals the models based on orthogonal array, Niyama criteria and GA/ANN.

Abstract: Due to their complexity, certain engineering problems like finding shock strength, Mach number etc. and the interaction of shock wave with a structure in free and restricted metal forming techniques cannot be achieved in a single experimentation, these can be obtained only through a number of trials and that leads to increase in cost and time. In such cases both cost and time can be reduced by adopting numerical simulations. In this projectcommercial software ANSYS is used to simulate the propagation shock wave through a shock tube, free and shape forming of metallic plates subjected to this shock wave. Shock Mach numbers up to 2.12 have been generated by varying the driver to driven pressure ratios. Thin copper plates of diameter 60mm and thickness of 0.5mm and 0.3mm are subjected to shock wave loadingin order to form into dies.These dies,madeof structural steel are modelled with pre-defined shapes. The plate peakoverpressures ranging from 9 to 20bar have been generated.The midpoint deflection, Von Mises stress and strain are calculated for free forming copper plates. The simulated results are compared with the experimental values available in literature. The simulated results match well with the experimental values.

Abstract: The aim at the present work is to study the consolidation behavior of Al and B4Ccomposite powder processed by Equal Channel Angular Pressing (ECAP) at room temperature. The composition of the composite powder is 95 wt% Al and 5 wt% B4C. The Al-B4C composite powder is subjected to ECAP through processing route A up to 4 passes. The ECAP die used for densification has 90° channel angle and 20° corner angle. It is found that the density and hardness of the composite are improved as the ECAP passes is increased. The microstructure is homogeneous and partial fragmentation of reinforcement is observed. Density and hardness measured after four ECAP are 97% and 98 HV. The improvement of density and hardness is the due strain enhances consolidation of powders during ECAP.

Abstract: An investigation was conducted to find the optimum aging temperature and aging time for Cu-Sn-Ni spinodal bronze alloys with varying nickel wt% cast in metal mould. The specimens were subjected to solutionisation and were aged at 250°C, 300°C, 350°C, 400°C and 450°C to induce spinodal decomposition. The microstructural observation reveals that the dendritic structure of the as-cast alloy was completely eliminated after solutionisation and grain boundary precipitates were formed with increase in aging time. The peak hardness and the peak aging time increases with increase in nickel content. This implies that nickel contributes to spinodal decomposition process.

Abstract: Powder Metallurgy (P/M) is a manufacturing process in which powders are compacted in a die to attain the final product. P/M has certain unique advantage like controlled porosity, High Strength to weight ratio. Aluminium (Al) is a light weight material, but pure Al does not possess a good strength. To achieve the strength, Copper (Cu) powders are blended at required proportions. Al along with Cu shows good mechanical properties. An attempt is made to optimize the process parameter of Al – 10% Cu powder to attain maximum process efficiency. Here optimization is done by Taghuchi’s method.

Abstract: This paper presents a novel approach for the optimization of input parameters on coated aluminum alloy 2024 T351 with Factor analysis method. These Experiments are conducted by varying the input parameters related to surface hardness and surface roughness. In this study, input parameters like coating thickness, substrate temperature and deposition rate are optimized with the considerations of multi responses such as surface hardness and surface roughness. L₄ orthogonal array was taken to conduct the experiments. The method shows a good convergence with the experimental and the optimum coating parameters where the maximum surface hardness and the minimum surface finish are obtained.

Abstract: We investigated multi objective optimization on age hardenable aluminum alloys (AA2024 and AA6061) using Taguchi based grey relational analysis (TGRA). We considered three significant process parameters such as rotational speed, welding speed, and axial force and evaluated the welding responses such as ultimate tensile strength and tensile elongation of fabricated weld specimens. Principal component analysis (PCA) was applied to estimate accurate weighting quality characteristics of each response in TGRA. Optimized process parameters were 1700rpm rotational speed, 60mm/min welding speed and 6kN axial force. Results of this approach will be useful in controlling the process parameters effectively.

Abstract: Metal Matrix Nano Composites (MMNC) consist of a metal matrix reinforced with nano-particles featuring physical and mechanical properties very different from those of the matrix. Especially carbon Nano tubes (CNT) can improve the matrix material in terms of wear resistance, damping properties and mechanical strength. The present investigation deals with the synthesis and characterization of aluminium matrix reinforced with micro B4C particles, and Multi Wall Carbon nano Tubes (MWCNT) were prepared by powder metallurgy route. Powder mixture containing fixed weight (%) of B4C and different wt% of MWCNT as reinforcement constituents that are uniaxial cold pressed and later green compacts are sintered in continues electric furnace. Microstructure and Mechanical properties such as micro hardness and density are examined. Micro structure of samples has been investigated using scanning electron microscope (SEM) .The results indicated that the increase in wt % of MWCNT improves the bonding and mechanical properties.